Tire-tread.



J. R. SANFORD & J. G. UGHTY.

TIRE TRE APPLICATION FILE 909.

929,632. Patented July 27, 1909.

UNITED STATES PATENT OFFICE.

JOSE-PH R. SANFORD AND JOHN G. DOUGHTY, OF'WI N STED, CONNECTICUT, ASSIGNORS TO THE FLEXIBLE RUBBER GOODS COMPANY, OF WIll'STED, CONNECTICUT, A CORPORATION or couuno'ncn'r.

Patented July 27, 1909.

TIBE IHEAD.

No. 929,632. Specification of Iietteni Patent.

Application filed January 6, 1909. Serial No. 470,980.

To all whom it may concern Be it known that we, J osEPrI R. SANFORD and JOHN G. DoUcH'rY, citizens of the United States, residing at Wmsted, county of Litchfield, State of Connecticut, have invented certain new and useful Improvements in Tire-Treads, of which the following is a full, clear, and exact description.

Our invention relates to improvements in tire treads, the same being of particular value and utility in connection with'cushion or pneumatic tires, so-called.

The purpose of the improved tread s to give superior traction, greater durability, easier riding and resistance to skidding, socalled. p

In the accompanying drawings Figure 1 is a sectional view of our improved tire. Fig. 2 is a development view of the tread laid out flat, the ends broken away.

1 represents the main body of the tire, in this instance of the pneumatic type, and provided with the usual fabric reinforcements 2. The tread of the tire is provided with a plurality of cupped projections 33--3 spaced apart and arranged in series extending around the tire and projecting beyond the solid portion thereof. There are by preference a plurality of series, two or more, three being shown in the drawings. The contact end of each cup 3 is preferably flat or substantially fiat,.as shown in Fig. 1, whereby a maximum surface engagement is obtained without undue flattening of the tire itself. By the employment of a flat tread, a much larger number of suction cups, are available for encountering the road surface at the point of contact withthe wheel than would be if the, tread were round.

It is to be observed in the sectional'view that the recess in each cup extendsdown very slightly below theplane of the bottom of the side walls of the cup, measured from the external base of the cup wall. The result is, when the projecting walls of the cup have worn away,.there will still be-a cavity retained in the tread 'of the tire where'eac cup was located which will still operate (though not as efficiently as when the wall is present) to aid traction and prevent skid- Tie action of the tread to secure superior traction is as follows: As the tread rolls'over the ground, the'road material fills the spaces around the walls of each cup and fumishes plane with the surface 0 thereby a better grip for the tire, whereby the vehicle may be driven ahead. Upon pavements, hard and smooth surfaces, superior traction is obtained by this tire in the following manner: As the tire rolls ahead one side of each cupis first slightly compressed, thereby displacing a portion of the air therein. When finally each cup presents its face squarely to the road, expansion occurs and suction takes place at each cup, tending to hold the tire to the road surface. The action of the tire in-preventing skidding is markedly increased on hard surfaces,

wet or slippery, the moist surface serving to individual cups in the adjacent series. This is best seen in Fig. 2. After long usage,

when the side walls of the. cups wear away,

it will be observed that there will still be left in the solid face of the tire a recess where each cup was formerly provided. The solid face of the tire would appear approximately on the line ac -w Fig. 1, and in said view it will be seen that the recesses project into the rubber to a point slightly elow said line.

We have found that by extending the re-' cess of the cup slightly below the main body of the tread it is more difficult to tearthe cup away from the tread than if the bottom of the recess is located ap roximately' on the f the main body of the tread. Consequently, by this featureof improvement, much greater strength and durability are added to the cupped extensions in addition to the advantages otherwise inentioned as growing out-of this deepening of the cup cavity. makes itself felt in that it renders the entire treadmore durable.

What we claim is:

A tire tread havin a. multitude of air chambers formed wit in and thereon, the major portion of each air chamber being formed by walls of circular cross-section,

This improvement also each circular wall being flat-ended and of substantial thickness throu hout and projecting beyond the body' 0 the tread, the multitude ofthefiat ends of the projection forming the wearing surface of the tread, each hollow projectlon standing alone and acting independently from the others increating vacuum and maintaining a suctionc0ntact.wi'th the road, the body of thetreed and the projections being molded integrally. 10

JOSEPH 3., SANFORD. JOHN GhDOUGHTY.

YVit-nesses:

WILBUR .G. MANCHESTER, LOUISE Br Ptmm. 

